/**
 *    Copyright (C) 2012 ZeroTurnaround LLC <support@zeroturnaround.com>
 *
 *    Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */
package com.smartandroid.sa.zip;

import java.io.File;
import java.io.FileFilter;
import java.util.ArrayList;
import java.util.Collection;

public final class ZTFileUtil {
	private ZTFileUtil() {
	}

	public static Collection<File> listFiles(File dir) {
		return listFiles(dir, null);
	}

	public static Collection<File> listFiles(File dir, FileFilter filter) {
		Collection<File> accumulator = new ArrayList<File>();

		if (dir.isFile()) {
			return accumulator;
		}

		if (filter == null) {
			// Set default filter to accept any file
			filter = new FileFilter() {
				public boolean accept(File pathname) {
					return true;
				}
			};
		}

		innerListFiles(dir, accumulator, filter);
		return accumulator;
	}

	private static void innerListFiles(File dir, Collection<File> accumulator,
			FileFilter filter) {

		String[] filenames = dir.list();

		if (filenames != null) {
			for (int i = 0; i < filenames.length; i++) {
				File file = new File(dir, filenames[i]);
				if (file.isDirectory()) {
					innerListFiles(file, accumulator, filter);
				} else {
					if (filter != null && filter.accept(file)) {
						accumulator.add(file);
					}
				}
			}
		}
	}
}
